The Neo Legacy to Neo N3 migration service resumed operation on Feb. 27 at 10:00am (UTC). The service had been paused due to a security breach that occurred on Feb. 8 affecting two N3 migration wallet addresses. It is believed the attacker was able to access the wallets through compromised private keys.
Approximately 3.4 million NEO, 730,000 GAS, and a mix of NEP-17 tokens were transferred from the migration wallets to three new addresses without corresponding migration transfers on Neo Legacy.
To limit damage to the Neo ecosystem and prevent token liquidation, the Neo Council elected to use the Policy native contract to block the three malicious addresses. Achieved via the signatures of 11 out of the 21 members, this prevented the vast majority of stolen funds from being accessed by the attacker.
Ultimately, the attacker was only able to clear approximately US $520 in fUSDT, fwETH, fwBTC, and FLM, which was bridged out of the ecosystem via Poly Network.
Neo has taken measures to secure the migration service, and all new asset migrations will be completed within 72 hours.
The announcement can be found below: